JP5205879B2 - Plunger pump - Google Patents

Description

  The present invention relates to an improvement in a plunger pump used as a hydraulic power source of an antilock brake system (ABS), a traction control system (TCS), or a stability control device. Specifically, the invention is intended to suppress an increase in the surface pressure of the rolling contact portion between the outer ring raceway and the rolling surface of each needle, and to improve the rolling fatigue life of each surface, regardless of the offset load applied due to an assembly error or the like. It is a thing.

When the ABS, TCS, or the like is activated, pressure oil is supplied to the wheel cylinder attached to the wheel regardless of the operation (depression) of the brake pedal, and the braking force is exerted on one or more wheels. At this time, the pressure oil supplied to the wheel cylinder is discharged from a plunger pump driven by a traveling engine or an electric motor and stored in an accumulator. As a plunger pump used in such a case, Patent Document 1 describes a structure as shown in FIG .

  In the plunger pump 1, a cam shaft 4 supported in a housing 3 by a pair of rolling bearings 2 and 2 is driven to rotate by a motor 5. A cam surface 6 that is eccentric with respect to the center of rotation of the cam shaft 4 is provided in the intermediate portion of the cam shaft 4 between the rolling bearings 2 and 2. The outer peripheral surface of the cam surface 6 has a cylindrical shape having a central axis that is eccentric with respect to the central axis of the cam shaft 4. Further, a cylindrical outer ring 7 is arranged around the cam surface 6 concentrically with the cam surface 6, and a plurality of needles 8, 8 are provided between the cam surface 6 and the inner peripheral surface of the outer ring 7. ing. Further, the base end surfaces of the plungers 9, 9 are abutted against the outer peripheral surface of the outer ring 7. The plungers 9 and 9 are given elasticity in the direction toward the cam surface 6 by return springs 10 and 10, respectively. When the cam shaft 4 is rotated by the motor 5, the plungers 9 and 9 are reciprocated in the cylinder cylinders 11 and 11 by the eccentric motion of the cam surface 6 and the elasticity of the return springs 10 and 10. And discharge the pressure oil.

In the case of the plunger pump 1 described in Patent Document 1 as described above, the outer ring 7 is provided with a so-called solid type formed by machining a metal material. On the other hand, Patent Documents 2 to 6 describe a structure including an outer ring called a shell, which is obtained by bending a metal plate. The use of a radial needle bearing having a shell-shaped outer ring is advantageous in terms of achieving both a high capacity and low cost of the plunger pump. FIG. 5 shows the plunger pump described in Patent Document 2. The shell type radial needle bearing 12 is formed by rolling a plurality of needles 8 and 8 on the inner diameter side of an outer ring 7a called a shell obtained by bending a metal plate. The outer ring 7a is made by subjecting a hard iron-based alloy plate material such as bearing steel and case-hardened steel to plastic processing such as deep drawing and burring. A pair of flange portions 14a and 14b formed in a state of being directed radially inward at both axial ends of the cylindrical portion 13 are provided. In the structure shown in FIG. 5 , an eccentric ring 15 is externally fixed to the cam shaft 4a in order to provide a cam surface 6a for the cam shaft 4a.

The shell-type radial needle bearing 12 having the outer ring 7a as described above is lower in cost of the outer ring 7a than the so-called solid-type radial needle bearing having the machined outer ring 7 as shown in FIG. At the same time, the thickness can be reduced. As long as the thickness can be reduced, the outer diameters and axial dimensions of the needles 8 and 8 can be increased under the same conditions (the radial and axial dimensions of the installation space are the same). The load capacity can be increased.

  However, in the case of the conventional structure as described above, regardless of whether the outer ring 7 or 7a is a solid type or a shell type, from the aspect of achieving both cost reduction and durability ensuring of the plunger pump, There is room for improvement in various ways. That is, in designing the plunger pump, the centers of the plungers 9 and 9 are positioned on the axial centers of the needles 8 and 8 constituting the radial needle bearing. The reason for this is that the radial load applied from the plungers 9, 9 to the outer rings 7, 7 a is positioned at the center of the needles 8, 8 in the axial direction, thereby rolling the needles 8, 8. This is because the surface pressure of the rolling contact portion between the surface and the outer ring raceways 16, 16a and the cam surfaces 6, 6a, which are the inner peripheral surfaces of the outer rings 7, 7a, is made uniform over the entire axial length.

However, there is a possibility that the centers of the plungers 9 and 9 and the axial centers of the needles 8 and 8 cannot be exactly matched due to problems in dimensional accuracy or assembly accuracy of the constituent members of the plunger pump. There is. If these centers do not coincide with each other, the surface pressure of the rolling contact portion between the rolling surface of each of the needles 8 and 8 and the outer ring raceways 16 and 16a and the cam surfaces 6 and 6a becomes the entire axial length. It becomes uneven. For example, as shown in FIG. 6A, a pair of plungers 9, 9 provided on the radially opposite side of the radial needle bearing 12 is moved from a predetermined position (designed position) to the shaft of the radial needle bearing 12. When the direction is shifted to the opposite side, a clockwise moment is applied to the outer ring 7a in FIG . As a result, regarding the needle 8 described in the upper part of FIG. 6A, the surface pressure of the rolling contact portion between the rolling surface and the outer ring raceway 16a and the cam surface 6a is excessive at the right end portion of the needle 8. (Edge load is added to the part). Further, regarding the needle 8 described in the lower part of FIG. 6A, the surface pressure of the rolling contact portion is excessive at the left end portion of the needle 8. The increase in surface pressure due to such a cause can occur regardless of whether the outer rings 7 and 7a are solid or shell-shaped.

Further, the outer ring 7a of the shell-shaped, since a low rigidity as compared with the outer ring 7 of the solid-shaped, as shown in FIG. 6 (B), the plungers 9, 9, the axial direction of the radial needle bearing 12 from the predetermined position Even when they are shifted to the same side, the surface pressure of the rolling contact portion may be excessive. That is, when a radial load is applied to the outer peripheral surface of the portion of the shell-shaped outer ring 7a having low rigidity that is disengaged from the axial center of each needle 8, 8, from the base end surface of each plunger 9, 9, the outer ring 7a presses one axial end portion {right end portion in FIG. 6 (B)} of the needles 8 and 8 while elastically deforming. As a result, the surface pressure of the rolling contact portion between the rolling surface and the outer ring raceway 16a and the cam surface 6a becomes excessive at one axial end portion of each of the needles 8 and 8.

  Even if the surface pressure of the rolling contact portion increases in any manner, if the surface pressure increases, the rolling surfaces of the needles 8, 8, the outer ring raceways 16 and 16 a, and the cam surfaces 6 and 6 a The rolling fatigue life of any one or a plurality of surfaces is reduced, and the durability of the radial needle bearing 12 and thus the plunger pump incorporating the radial needle bearing 12 is impaired. Of course, if the dimensional accuracy of each component of the plunger pump and the assembly accuracy of these members are increased, and the centers of the plungers 9 and 9 and the axial centers of the needles 8 and 8 are exactly matched, None of the above-described aspects occur, and an increase in the surface pressure of the rolling contact portion can be suppressed. However, since the processing and assembly of the above members are both troublesome and cause the manufacturing cost of the plunger pump to increase, it is not preferable to extremely increase the respective accuracy.

JP 2005-240654 A JP 2000-73938 A JP 2000-356191 A Special table 2003-502603 gazette US Pat. No. 5,230,275 US Pat. No. 6,550,971

  In view of the circumstances as described above, the present invention suppresses an increase in the surface pressure of the rolling contact portion between the rolling surface of each needle and the outer ring raceway and the cam surface, thereby improving the rolling fatigue life of each surface. The pump was invented to be realized at low cost without the necessity of extremely increasing the dimensional accuracy and assembly accuracy of each component.

  The plunger pump of the present invention includes a cam shaft, a cam surface having a circular cross section, which is provided on the outer peripheral surface of the cam shaft and is eccentric with respect to the rotation center of the cam shaft, and is concentric with the cam surface around the cam surface. A cylindrical outer ring, a plurality of needles provided between the outer ring raceway, which is the inner peripheral surface of the outer ring, and the cam surface, and a base end surface that projects from the outer peripheral surface of the outer ring. A contact plunger. The cam surface may be formed as an integral part of the cam shaft, or may be configured by externally fitting and fixing a separate eccentric ring with the outer peripheral surface as a cam surface. However, either may be sufficient.

In particular, in the plunger pump of the present invention, the cam surface has a crowning shape. The crowning shape, protrudes to the rolling surface of most the needles is axially intermediate portion, and gradually inclined in a direction away from the rolling surface of the needles toward the axially opposite end portions, is in cross section convex arcuate . Specifically, a single convex curved surface (full crowning shape) having a single radius of curvature over the entire length in the axial direction, or an axis having a large radius of curvature (∞, that is, a cylindrical surface whose generatrix shape is a straight line) A compound curved surface (partial crowning shape) in which a middle portion in the direction and both end portions in the axial direction having a small radius of curvature are smoothly continuous can be employed. It does not matter whether the rolling surface of each needle has a crowning shape.

Moreover, in the case of this invention , the holder | retainer for hold | maintaining said each needle | hook so that rolling is possible is provided. This cage is arranged parallel to each other in the axial direction at both ends in parallel with each other and a pair of rim portions each having an annular shape, spaced apart from each other in the circumferential direction. A plurality of column portions each having both end portions coupled to the both rim portions, and a portion surrounded by each of the four circumferences by the column portions adjacent to each other in the circumferential direction and the both rim portions. This is a pocket for holding the needle. Then, positioning in the radial direction of the cage is achieved based on the engagement between the inner edge of the rim portion in the axial direction and the crowned portion of the cam surface.
In addition, the outer ring used in practicing the present invention may be a solid type or a shell type. However, as in the invention described in claim 2, a shell type, that is, a metal plate is bent. Thus, it is effective to provide a pair of flange portions facing radially inward at both axial ends of the cylindrical portion.

According to the present invention configured as described above, a plunger pump capable of suppressing an increase in the surface pressure of the rolling contact portion between the rolling surface of each needle and the outer ring raceway and the cam surface and improving the rolling fatigue life of each surface. Can be realized.
That is, in the case of the plunger pump of the present invention, when the line of action of the radial load applied from each plunger to the outer peripheral surface of the outer ring deviates from the center of each needle in the axial direction , while shifting the rolling contact portion between the rolling surface in the axial direction, the central axis of the central shaft and the needles of the camshaft provided with the cam surface is not parallel. Based on the presence of the crowning shape, the surface pressure of the rolling contact portion between the both surfaces gradually decreases toward the axial end of the rolling contact portion. As a result, the surface pressure of the rolling contact portion between the rolling surface and the outer ring raceway and the cam surfaces of the needles, based on the edge load prevented from becoming excessive, these rolling surfaces and the outer ring raceway, the cam surface The rolling fatigue life can be secured.

In addition, regarding the rolling contact portion between the outer ring raceway which is the inner circumferential surface of the outer ring and the rolling surface of each needle, the occurrence of edge load can be suppressed for the following reason. That is, when an offset load is applied from the plunger to the outer peripheral surface of the outer ring, the needles are inclined based on the crowning shape of the cam surface . Then, the outer ring is inclined to follow the the needles, there is no possible the axial end portion of the axial end portion and the outer ring raceway of the rolling surface of the needles is adjoining particularly strong person, durability The occurrence of edge load that leads to a decrease can be suppressed. Therefore, even in a structure in which only the cam surface is crowned, and both the rolling surface and the outer ring raceway are cylindrical surfaces, durability can be improved as compared with the conventional structure. Of course, if the inner ring surface of the outer ring is also crowned, the occurrence of edge load at the rolling contact portion between the outer ring raceway and the rolling surface of each needle can be more effectively prevented.

Further, in the present case, with the cam surface crowning shape, since the aim of radial positioning of the retainer by the engagement of the rim portion of the pair the crowning profile part, following such effects Can be obtained. First, at the time of assembling the plunger pump, it is possible to prevent collision between the axial end of each needle and the end of the cam surface. That is, based on the crowning shape, the outer diameter of the axial end of the cam surface can be clearly smaller than the diameter of the inscribed circle of each needle. For this reason, for example, when an eccentric ring provided with the cam surface is inserted into the inner diameter side of each needle, the axial end edge of the eccentric ring and the axial end of each needle are made difficult to abut. The insertion work can be performed easily. In addition, these edges strongly collide with each other during the insertion work, and the metal pieces, etc. that are chipped off due to the collision are prevented from entering into lubricants such as grease. However, the durability of the plunger pump can be improved.

Further, in order to position the cage in the radial direction, the inner edge of the pair of rims is engaged with the inner edge of the axial direction and the crowning-shaped part, so that power loss is reduced. Moreover, it is possible to realize a plunger pump that can keep the operation noise low. That is, by holding each needle so as to be freely rollable by a cage, it is possible to prevent friction between the rolling surfaces of adjacent needles in the circumferential direction and reduce the rotational resistance (dynamic torque) of the radial needle bearing. . Further, the radial displacement of the cage can be suppressed to suppress the vibration of the cage, and the generation of noise based on the vibration can be suppressed. In addition, since the area (friction area) of the portion where the both rim portions and the cam surface are closely opposed to each other is suppressed based on the presence of the crowning shape, the above-described viscosity resistance of the lubricant present in this portion is reduced. The rotational resistance of the radial needle bearing can be reduced. As a result, power loss can be reduced, and driving noise can be reduced.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention corresponding to claims 1 and 2 . The feature of the present invention is that the edge load is not applied to the rolling contact portion inside the radial needle bearing even when the plunger is a part of the outer peripheral surface of the outer ring and presses the portion of each needle that deviates from the center in the axial direction. It is in the point to do. Since the structure of the plunger pump is the same as the structure known from the prior art, such as the structure described in Patent Documents 1 to 6, description thereof will be omitted, and the following description will focus on the features of the invention. .

In the case of this example, the cam surface 6b, which is the outer peripheral surface of the eccentric ring 15a, has a crowning shape as shown exaggeratedly in FIG. On the other hand, the rolling surfaces of the needles 8 and 8 are not particularly crowned, and are simply cylindrical surfaces except for the chamfered portions at the outer peripheral edges at both ends in the axial direction. Further, the outer ring raceway 16a formed on the inner peripheral surface of the outer ring 7a is also a simple cylindrical surface except for curved portions at both ends in the axial direction. The outer ring 7a is formed by bending a metal plate, and is provided with a pair of flange portions 14a, 14b facing inward in the radial direction at both axial end portions of the cylindrical portion 13. It is. In particular, in the case of the structure of the present example, the cam surface 6b has a crowning shape, and the outer diameter of the cam surface 6b is the largest in the middle portion in the axial direction and gradually decreases toward both ends in the axial direction. That is, the cam surface 6b is a single convex curved surface having a single radius of curvature over the entire axial length. The eccentric ring 15a having such a cam surface 6b constitutes a plunger pump by being externally fitted and fixed to the cam shaft. The operation of processing the cam surface 6b into a crowning shape is performed after an eccentric hole for fitting the cam shaft 4a (see FIGS. 5 to 6 ) is formed in the eccentric ring 15a . It is preferable from the viewpoint of ensuring the accuracy of the cam surface 6b.

  Further, the needles 8 and 8 are held by a cage 17 so as to be freely rollable. This cage 17 is a so-called saddle cage, and is formed integrally by injection molding a synthetic resin having a low coefficient of friction and oil resistance, and a pair of rim portions 18, 18 and And a plurality of column parts 19, 19. Both the rim portions 18 and 18 are annular with the same diameter, and are provided concentrically and in parallel with each other in a state of being separated in the axial direction. The column portions 19 and 19 are arranged in parallel with each other with a space therebetween in the circumferential direction, and both ends of the column portions 19 and 19 are coupled to the rim portions 18 and 18, respectively. Then, a pocket 20 for holding the needles 8 and 8 so that the needles 8 and 8 can roll freely in a portion surrounded by the circumferences of the column parts 19 and 19 and the rim parts 18 and 18 in the circumferential direction. , 20.

  In the case of this example, in order to position the retainer 17 in the radial direction by engaging the inner peripheral surfaces of the rim portions 18 and 18 with the cam surface 6b, the inner diameters of both the rim portions 18 and 18 are set. This is restricted in relation to the outer diameter of the cam surface 6b. In the case of this example, the inner peripheral surfaces of both the rim portions 18 and 18 are cylindrical surfaces whose inner diameters do not change in the axial direction (or partial conical concave surfaces inclined in a direction in which the inner diameter gradually increases toward both axial end portions. ). Accordingly, the distance between the inner peripheral surfaces of the rim portions 18 and 18 and the cam surface 6b is the axial inner end edge of the inner peripheral surfaces of the rim portions 18 and 18 (the axial center of the cage 17). It is the shortest at the end edge) and gradually becomes longer toward the outside in the axial direction. Therefore, the inner diameter of both the rim portions 18, 18 is set to be larger than the outer diameter of the cam surface 6b where the axial inner end edges of the inner peripheral surfaces of the rim portions 18, 18 are opposed in the radial direction. Slightly larger. Therefore, the radial position of the cage 17 is regulated based on the engagement between the inner edge of the rim portions 18 and 18 and the crowned portion of the cam surface 6b. (The cage 17 does not swing in the radial direction as it rotates). Even when the inner diameters of both the rim portions 18 and 18 are smaller than the maximum diameter of the cam surface 6b, the difference is that the rim portion 18 is expanded while elastically expanding the inner diameter of one of the rim portions 18. It is suppressed to such an extent that it can get over the maximum diameter portion of the cam surface 6b.

According to the structure of the present example configured as described above, the surface pressure of the rolling contact portion between the rolling surface of each of the needles 8 and 8 and the outer ring raceway 16a and the cam surface 6b can be reduced while suppressing the manufacturing cost. It is possible to suppress the rise and improve the rolling fatigue life of these surfaces.
That is, even if the central axis of the outer ring 7a and the central axis of the eccentric ring 15a are somewhat non-parallel, the rolling surfaces of the needles 8, 8 and the cam surface 6b and the outer ring raceway 16a roll. There is no occurrence of damage that leads to a decrease in durability such as early peeling at the contact portion. This point will be described with reference to FIG.

First, as shown in FIG. 2A, when a pair of plungers 9 and 9 provided on the radial direction opposite side of the radial needle bearing are displaced from the predetermined position to the opposite side with respect to the axial direction of the radial needle bearing. A clockwise moment is applied to the outer ring 7a in FIG. In this state, the central axis of the outer ring 7a and the central axis of the cam surface 6b are not parallel, but the cam surface 6b is crowned so that the rolling surfaces of the needles 8 and 8 The cam surface 6b is kept in a rolling contact with the axial direction intermediate portion of each of the needles 8 and 8 . The axial ends of the rolling surfaces of the needles 8 and 8 and the cam surface 6b are in rolling contact with each other, and no edge load is applied to the portions. In this case, the needles 8 and 8 are inclined following the outer ring 7a, and the central axes of the needles 8 and 8 are kept parallel to the central axis of the outer ring 7a. For this reason, the rolling contact surfaces of the needles 8 and 8 and the outer ring raceway 16a are in contact with each other almost uniformly over the entire axial length of the rolling contact surfaces of the needles 8 and 8. Therefore, no edge load is applied to the rolling contact portion between the rolling surface of each of the needles 8 and 8 and the outer ring raceway 16a.

Further, as shown in FIG. 2B, the plungers 9, 9 are displaced from the predetermined positions to the same side in the axial direction of the radial needle bearing, and the needles 8, 8 are elastically deformed while the outer ring 7a is elastically deformed. Even when one axial end portion {the left end portion in FIG. 2B) is pressed, the needles 8 and 8 are inclined along the outer ring raceway 16a while the axial intermediate portions of the respective rolling surfaces are inclined. The cam surface 6b is brought into rolling contact. Therefore, even in the state shown in FIG. 2B, an excessive surface pressure based on the edge load acts on the rolling contact portions of the rolling surfaces of the needles 8, 8 and the outer ring raceway 16a and the cam surface 6b. There is no.
For this reason, the rolling surfaces of the needles 8 and 8, the outer ring raceway 16 a, and the cam can be obtained without extremely increasing the dimensional accuracy of the constituent members of the plunger pump and the assembly accuracy of these members. Rolling fatigue life with the surface 6b can be secured, and the durability of the radial needle bearing, and thus the plunger pump incorporating the radial needle bearing can be secured.

  In the case of the structure of this example, the cam surface 6b is crowned, and the retainer 17 is positioned in the radial direction by engaging the crowned portion with the pair of rim portions 18, 18. Therefore, the assembly work of the plunger pump can be facilitated, the durability can be improved, the operation noise can be reduced, and the efficiency can be improved.

  Of these, the ease of assembling and the improvement of durability prevent the abutting between the axial ends of the needles 8 and 8 and the axial end of the cam surface 6b when the plunger pump is assembled. Can be achieved. That is, based on the crowning shape, the outer diameter of the end portion in the axial direction of the cam surface 6b can be clearly smaller than the diameter of the inscribed circle of the needles 8 and 8. For this reason, when the eccentric ring 15a provided with the cam surface 6b is inserted into the inner diameter side of the needles 8 and 8, the axial end edge of the eccentric ring 15a and the axial end portions of the needles 8 and 8 are inserted. Can be easily inserted, and insertion can be performed easily. Further, the edge and the end strongly collide with the insertion work, and it is possible to prevent the metal pieces and the like that have been chipped off due to the collision from being mixed into the lubricant such as grease. The lubrication of the radial needle bearing that constitutes the plunger pump is carried out with grease enclosed in the cam mechanism, and this grease does not change over a long period of time. The durability of the mechanism part is impaired. On the other hand, in the case of the structure of this example, it is possible to prevent hard foreign substances that cause such a decrease in durability during the above assembling work from being mixed into the grease, thereby improving the durability of the plunger pump. Can be planned.

  Further, the operation noise is reduced and the efficiency is improved by positioning the retainer 17 in the radial direction with respect to the inner peripheral surface of the pair of rim portions 18 and 18 and the cam surface 6b. It can be obtained by engaging with the crowning-shaped part. That is, the needles 8 and 8 are held by the cage 17 so as to be able to roll, thereby preventing friction between the rolling surfaces of the needles 8 and 8 adjacent in the circumferential direction. Rotational resistance (dynamic torque) can be reduced. Further, the radial displacement of the cage 17 can be suppressed to suppress the vibration of the cage 17 even when the radial needle bearing is operated at a high speed, and the generation of noise based on the vibration can be suppressed. In addition, since the area (friction area) of the portion where the rim portions 18 and 18 and the cam surface 6b are close to each other is suppressed based on the presence of the crowning shape, the viscosity of the grease present in this portion is reduced. The rotational resistance of the radial needle bearing due to resistance (shear resistance acting on the grease film) can be reduced. As a result, power loss can be reduced, and driving noise can be reduced.

[Second Example of Embodiment]
FIG. 3 shows a second example of an embodiment of the present invention corresponding to claims 1 and 2 . In the case of this example , the cam surface 6b which is the outer peripheral surface of the eccentric ring 15a has a crowning shape, and the rolling surfaces of the needles 8a and 8a also have a crowning shape. In the case of such a structure of this example, an increase in the surface pressure at the rolling contact portion between the rolling surface of each of the needles 8a and 8a and the outer ring raceway 16a and the cam surface 6b can be suppressed more effectively. The rolling fatigue life of these surfaces can be improved.

The plunger pump and the radial needle bearing for the plunger pump of the present invention can be applied not only to pressure oil supply for controlling ABS, TCS, etc. but also to plunger pumps for various mechanical devices.
Further, the portion of the cam shaft provided with the cam surface may be integrated with other portions, or a separate cam (eccentric ring) may be externally fixed to the rotating shaft. The structure for external fitting fixation may be interference fitting (including shrink fitting, cold fitting, etc.), key engagement, spline engagement, or the like.

The fragmentary sectional view which shows the state which combined the cam and radial needle bearing which comprise the plunger pump which show the 1st example of embodiment of this invention. The fragmentary sectional view which shows two examples of the state where the center of the plunger deviated with respect to the center of each needle in the structure of this first example. The fragmentary sectional view which shows the 2nd example of embodiment of this invention. Sectional drawing which shows the 1st example of the plunger pump conventionally known. The fragmentary sectional view which shows the 2nd example. The fragmentary sectional view which shows two examples of the state which the center of the plunger deviated with respect to the center of each needle with the structure of this 2nd example.

DESCRIPTION OF SYMBOLS 1 Plunger pump 2 Rolling bearing 3 Housing 4, 4a Cam shaft 5 Motor 6, 6a, 6b Cam surface 7, 7a, 7b Outer ring 8, 8a Needle 9 Plunger 10 Return spring 11 Cylinder cylinder 12 Shell type radial needle bearing 13 Cylindrical part 14a, 14b collar part 15, 15a eccentric ring 16, 16a outer ring raceway 17 cage 18 rim part 19 pillar part 20 pocket

Claims (2)

A cam shaft, a cam surface having a circular cross-section eccentric to the rotation center of the cam shaft provided on the outer peripheral surface of the cam shaft, and a cylindrical outer ring disposed concentrically with the cam surface around the cam surface And a plurality of needles rotatably provided between the outer ring raceway that is the inner peripheral surface of the outer ring and the cam surface, and a plunger that abuts the base end surface against the outer peripheral surface of the outer ring. In the plunger pump, the cam surface is inclined in the direction in which the axial middle portion protrudes most from the rolling surface of each needle and gradually moves away from the rolling surface of each needle toward the both end portions in the axial direction. It has a crowned shape with a convex arc shape in cross section, and is equipped with cages for holding these needles in a freely rolling manner. These cages are arranged in parallel with each other at both ends in the axial direction. A pair of rims and a circle A plurality of pillars that are arranged in parallel with each other in a state of being spaced apart from each other and that have both ends connected to the two rims, the pillars adjacent to each other in the circumferential direction, and both the rims; A portion surrounded by each of the four circumferences is used as a pocket for holding the needles, and the inner peripheral edge of both rim portions is the inner edge of the axial direction and the crowning shape of the cam surface. A plunger pump characterized in that positioning in the radial direction of the cage is achieved based on engagement with a portion . 2. The plunger according to claim 1, wherein the outer ring is formed by bending a metal plate and is provided with a pair of flange portions facing radially inward at both axial end portions of the cylindrical portion. pump.

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